CAREER: Interplay of sliding ferroelectricity, spin and charge orderings in layered quantum materials

Non-technical abstract: This project focuses on understanding of properties of a new class of quantum materials with unique properties, known as two-dimensional layered materials. By modeling, characterizing, and engineering the novel physics, this research aims to understand the materials properties and achieve their control. These materials can establish a new platform for energy-efficient and high-speed memory and logic devices, and compact and programmable quantum simulators to address the growing information and energy demands. Integrated with the research, the project aims to promote participation in STEM, focusing on undergraduates and K-12 teachers, including from rural areas in Wisconsin. The PI partners with the Materials Research Science and Engineering Centers (MRSEC) education group and Engineering EXPO at the University of Wisconsin-Madison to organize “2D ferroelectrics for energy-efficient future” education and outreach program including nanomaterials research, STEM education activities development for high school classrooms, and professional development seminars. Technical abstract: Two-dimensional (2D) layered materials are promising quantum material platforms with many important electronic properties, such as magnetism, strong electron correlation, superconductivity, and ferroelectricity. However, the interplay of ferroelectricity and other quantum properties is significantly unexplored because most current 2D quantum materials are nonpolar. Such scarcity hinders many exciting research subjects such as 2D multiferroics, dipolar Hubbard model, reconfigurable charge orderings, and superconducting diode effects. Recent discoveries of “sliding ferroelectricity” from polar stacking of nonpolar layers indicate it is possible to design ferroelectrics out of the vast majority of 2D materials with parent nonpolar compounds. The ferroelectricity can be switched via interlayer sliding, where the ultralow van der Waals sliding barrier is much smaller than that of any other ferroelectrics. The PI’s approach is to design and assemble various nonpolar 2D magnetic monolayers into polar stacking structures, where spin and charge orderings are hypothesized to be sensitive to ferroelectricity-driven stacking evolution. To fully understand the new quantum orderings and coupling physics, the research team use an in-house multimodal optical, electrical, and magnetic characterization platform to enable simultaneous access to ferroelectricity, magnetism, and electron correlation at various spatial, temporal, and energy scales. Furthermore, the PI will quantify and dynamic control of coupling strength by electrostatic doping and ultrafast light engineering. The research will advance the understanding of many-body interplay in two-dimensional quantum materials and pave the way for device applications using developed polar and Moiré 2D magnets in low-power electronics, ultrahigh-speed spintronics, and reconfigurable quantum simulation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.